88 Mercury 115hp inline 6 carb question

The motor is on my pontoon boat. At the lake I noticed it down on power, but actually sounded OK and my tach is a little flakey anyhow (it works, but intermittantly). When I returned home and removed the engine cover I noticed there was a samll hose (vacume??) on the center carb that is split and not attached. On the other two, it goes from a fitting on one side of the carb to a fitting on the other side.

Can anyone tell me what the hose is and what it would do to performance if not attached?? I'm pretty sure the tach issue is a bad ground or connection problem somewhere and not related to this. Thanks

Re: 88 Mercury 115hp inline 6 carb question

The small, short (~2-3 inches) hose on the carb is the backdrag hose. If it is torn or missing, that carb would run lean. You want to replace it.

it will have no effect on your tach.....

Re: 88 Mercury 115hp inline 6 carb question

Thank you. I have replaced it, but have not run it yet. Would it lean out far enough to hurt anything or just make it run poorly? I appreciate the info, thanks again. gk

Re: 88 Mercury 115hp inline 6 carb question

My Merc 115hp from 1984, had some severe problems getting hole shot without bad hesitation in the lower to mid rang rpms. And did only run best over 3500 rpm and up to 5500-6000 depending on the propeller.
I solved this with adding over size main jets, original was 0.074 and is now running 0.082.
I also lowered the WOT ignition point from 21 dg to 19 dg.
And then gave the idle adjustment screws plenty of opening without killing it. Idle has to be rich in mixture in these old motors.
All this did the trick for me, it is running 100%, and this without idle stabilizer box, which only caused lots of trouble.
Hole shot is now no problem without any hesitation.